Silicon etching liquid and etching method

Abstract

A silicon etching liquid characterized by anisotropically dissolving monocrystalline silicon therein by using an aqueous solution containing a quaternary ammonium hydroxide and an aminoguanidine salt and an etching method of silicon using the instant etching liquid are an etching liquid and an etching method enabling one to perform processing at a high etching rate in etching processing of silicon, particularly in etching processing of silicon in a manufacturing process of MEMS parts or semiconductor devices.

The invention claimed is: 
     
       1. A silicon etching method, said method comprising etching an etching object comprising monocrystalline silicon by immersing said object with a silicon etching aqueous solution consisting essentially of:
 (1) a quaternary ammonium hydroxide, 
 (2) an aminoguanidine salt, and 
 (3) water 
 
       to anisotropically dissolve said monocrystalline silicon, wherein the aminoguanidine salt (2) is at least one selected from the group consisting of aminoguanidine bicarbonate, aminoguanidine sulfate, animoguanidine hydrochloride and aminoguanidine nitrate. 
     
     
       2. The silicone etching method for anisotropically dissolving monocrystalline silicon according to  claim 1 , wherein the quaternary ammonium hydroxide (1) is tetramethylammonium hydroxide. 
     
     
       3. The silicone etching method for anistropically dissolving monocrystalline silicon according to  claim 1 , wherein a concentration of the quaternary ammonium hydroxide (1) is from 3 to 30% by mass, and a concentration of the aminoguanidine salt (2) is from 1 to 20% by mass, based on the total weight of the solution. 
     
     
       4. The silicone etching method for anisotropically dissolving monocrystalline silicon according to  claim 1 , wherein a pH of the solution is 11 or more. 
     
     
       5. The silicon etching method according to  claim 1 , wherein the silicon etching aqueous solution consists essentially of:
 (1) tetramethylammonium hydroxide, 
 (2) aminoguanidine bicarbonate, and 
 (3) water. 
 
     
     
       6. The silicon etching method according to  claim 1 , wherein the silicon etching aqueous solution consists essentially of:
 (1) tetramethylammonium hydroxide, 
 (2) aminoguanidine sulfate, and 
 (3) water. 
 
     
     
       7. The silicon etching method according to  claim 1 , wherein the silicon etching aqueous solution consists essentially of:
 (1) tetramethylammonium hydroxide, 
 (2) animoguanidine hydrochloride, and 
 (3) water. 
 
     
     
       8. The silicon etching method according to  claim 1 , wherein the silicon etching aqueous solution consists essentially of:
 (1) tetramethylammonium hydroxide, 
 (2) aminoguanidine nitrate, and 
 (3) water. 
 
     
     
       9. The silicon etching method according to  claim 1 , wherein the temperature of the silicon etching aqueous solution is 40° C.-90° C.